A judge on Friday struck down a 33-year-old Maryland law against same-sex marriage, agreeing with 19 gay men and women that it violates the state constitution's guarantee of equal rights.

"Although tradition and societal values are important, they cannot be given so much weight that they alone will justify a discriminatory statutory classification," Judge M. Brooke Murdock wrote.

The judge immediately stayed the order to give the state time to appeal.

The ruling came in a lawsuit filed in 2004 by the American Civil Liberties Union on behalf of nine couples and a man whose partner died. It named court clerks in Baltimore city and Prince George's, St. Mary's, Dorchester and Washington counties as defendants.

The state law specifying that marriage is a union of one man and one woman was passed in 1973.

Plaintiffs' lawyers argued in court that the ban violates equal rights guaranteed by the state constitution. Lawyers for the state said the issue was a matter for the Legislature and not the courts.

The ruling is expected to be appealed to Maryland's highest court, the Court of Appeals.